A modern paper machine is equipped with various finishing units e.g. calenders and coating units in order to produce better optical and printing properties. To accomplish these required properties paper is manipulated between two parallel mounted rolls. The contact area of these rolls is called a nip. The rolls are pressed together using hydraulic loading mechanism in order to achieve required pressure to paper web between the rolls. One of the most important nip unit driving parameter is linear load i.e. force per length. To compensate deflections, which are caused by line load and gravity, the rolls are crowned. In cases, where the total nip force surpass the gravity force of the roll the zero load condition exists. In the other words the roll floats freely and bearing clearances can place themselves arbitrary. To prevent misalignment due to bearing clearances and to achieve more accurate line load control a new closing procedure has been developed. The actual line load level is force-controlled while the approach maneuver of the roll is controlled using positioning sensors. Tampere University of Technology (TUT) has built up an experimental set-up to study both vibration phenomena and behavior of polymer roll cover material. This paper presents the equations and experimental results of a new nip closing procedure.

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